21043901 has 2 divisors, whose sum is σ = 21043902. Its totient is φ = 21043900.

The previous prime is 21043871. The next prime is 21043927. The reversal of 21043901 is 10934012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17023876 + 4020025 = 4126^2 + 2005^2 .

It is a cyclic number.

It is not a de Polignac number, because 21043901 - 2¹⁰ = 21042877 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21043991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10521950 + 10521951.

It is an arithmetic number, because the mean of its divisors is an integer number (10521951).

Almost surely, 2^21043901 is an apocalyptic number.

It is an amenable number.

21043901 is a deficient number, since it is larger than the sum of its proper divisors (1).

21043901 is an equidigital number, since it uses as much as digits as its factorization.

21043901 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 21043901 is about 4587.3631859708. The cubic root of 21043901 is about 276.0845370462.

Adding to 21043901 its reverse (10934012), we get a palindrome (31977913).

It can be divided in two parts, 2 and 1043901, that multiplied together give a palindrome (2087802).

The spelling of 21043901 in words is "twenty-one million, forty-three thousand, nine hundred one".